1. Field of the Invention
The present invention relates to reduced-friction surface assemblies particularly suited for use as artificial ice skating rinks.
2. Description of the Related Art
The sport of ice skating enjoys wide popularity and is widely practiced. The practice of or exhibition of this sport on natural ice requires either the provision of an outdoor rink of suitable size or the provision of an indoor rink. The construction and maintenance of outdoor rinks are dependent on the vagaries of weather and such rinks are impractical in warm climates or during warm seasons. On the other hand, enclosed or indoor rinks using natural ice require the installation of extensive refrigeration systems to keep the ice surface at the proper temperature and prevent melting. Whether outdoor or indoor, ice skating rinks composed of natural ice also require periodic resurfacing to maintain an ice surface that is smooth and even enough to permit skating. Such resurfacing is normally accomplished by an expensive self-propelled ice surface refinishing machine, often referred to as a Zamboni machine.
To overcome these difficulties, several types of artificial skating rinks have been proposed in the past. For example, U.S. Pat. No. 3,771,891 to Nirenski et al. teaches an artificial ice skating rink formed of square panels of plastic sheet material joined together by cooperating tongues and channels integrally formed on the edges of the panels, in which the tongue-and-channel edges of the panels must be carefully machined for a precise fit so that when they are joined together, no cracks or ridges are formed at the seams where the panel edges of separate adjoining panels are brought together. U.S. Pat. No. 3,771,891 to Nirenski et al. further requires that the panels are clamped together by pairs of opposing channel members retained around the periphery of the rink assembly and drawn together by a grid of steel straps running along the underside of the rink that are clamped under tension at the channel members. From standpoints of equipment and labor requirements during installation, it would be desirable to eliminate the need for extraneous fastening and clamping means in assembling an artificial ice skating rink.
U.S. Pat. No. 4,169,688 to Toshio purports to teach an artificial ice-skating rink flooring including one embodiment in which a plurality of plastic plates are provided with edge channels and common insertion pieces of a metal or synthetic resin or the like are fitted into respective confronting panel channels, and thereafter, bores must be made extending through the plates and insertion pieces into which are inserted fixing pins and the pin heads are then cut off to be smoothly leveled with the plate surfaces. However, the necessity of such fixing pins makes the assembly or disassembly of the skating rink more complicated and labor intensive. In a second embodiment of U.S. Pat. No. 4,169,688 to Toshio, the plates must be arranged upon a cushion material layer, and the plates are then either joined using U-shaped, T-shaped, or tapered-shaped insertion pieces or, alternatively, adhesive tape must be deployed beneath the plate seams where no mechanical hook-like interlock is created between the channels and insertion piece. The need to use a cushion layer in the second embodiment of the Toshio '688 patent raises costs and increases labor, and further, the need to form complex three-dimensional shapes for the insertion pieces and complementary channel shapes in the plate edges can be expected to increase the manufacturing cost and complexity, while the alternate use adhesive tape at the plate seams raises cost and increases labor.
Moreover, the interlocking design used in one of Toshio's designs (see FIGS. (9A-B) can be expected to experience cracking, breaking and buckling at the complexly-shaped connection splines. Ice skating rink assembly materials experience expansion and contraction, and forces exterted by skaters must be absorbed by ice skating flooring. Namely, expansion and contraction mismatches between the various parts of the assembly can be expected to lead to problems, such as buckling, as well as plastic breakage and/or embrittlement problems for any small plastic pieces used on a connecting spline that will tend to absorb stresses from an adjoining larger plastic panel mass. Consequently, it can be expected that the complexly-shaped, yet small plastic pieces that are supposed to fit in an interlocking pattern in the Toshio patent increase the risk that the assembly will fail. In a third embodiment of the Toshio '688 patent, the plates again are assembled on a cushion layer with the edges of plates being fused or heat bonded together. Such a heat-bonding operation would require special equipment and it would create a permanently integrated rink structure that would be difficult to disassemble, if later necessary or desired.
A low-friction composite structural element for an artificial ice skating rink is also the subject of U.S. Pat. No. 5,387,343, which was invented by two of the current named inventors. That prior design and construction generally involved panels each formed as a laminate of thin polyolefin plastic layers (for example, 4-7 mm) adhered on both sides of a thick central wood core piece. These composite panels were assembled together with a channel-and-spline arrangement using a plastic spline inserted within a channel formed by the wood cores of adjacent panels. For the prior design, certain improvements were made to the formulations of the relatively thin plastic surface layers and adhesives used in the laminating process associated with that invention, as compared to the prior art.
However, a problem encountered with the prior wood-core based design of U.S. Pat. No. 5,387,343 is that it can not survive well in outdoor skating environments. Namely, exposure to water, high humidity, and other sources of moisture was found to cause undesirable swelling of the wood cores of the composites. Additionally, prolonged exposure to water was found to create mold, mildew and eventually wood rotting problems. This water damage to the wood core component of our prior design eventually made the panel assembly unstable and unsuitable for ice skating. Another problem associated with the prior plastic-wood composite panel structure was incompatibility caused by the mismatch in the expansion and contraction behavior of the two different laminate materials involved. The wood expanded and contracted at a slower rate than the plastic (for example, polyethylene), thus causing the thin (4-7 mm) plastic surface sheet to delaminate from the wood core, no matter what adhesive was used. As the thin plastic sheet separated, it would begin to curl, making skating dangerous if not impossible.
Therefore, a need exists for an improved artificial ice skating surface that is easier and less costly to manufacture, install and maintain which eliminates the prior art problems of buckling, delamination and/or water damage problems while still meeting performance requirements in terms of durability, stability, low wear, low water absorption, low surface friction, and high surface consistency so as to be suitable for skating.